It is said that the EXTERNALITY is the consequence of an action being taken on others in the form of profit or expense without being calculated at the market price of the commodity and it is usually unintentional and unelected. In this article with descriptive–, analytical method it has been answered: what is the pattern of Iran legal system related to the environment to compare with the EXTERNALITY? It has been more emphasis on “, licenses”,or “, punishment”,pattern? The research findings are first,The primary focus of the Iranian legislative system is on the "punitive model" and the pattern of permissions is not institutionalized Therefore, the recent pattern faces many obstacles. This pursuit viewpoint is incompatible even with the main objectives of the judiciary (sections 2 and 5 of article 156 of constitution). Second,it not used the balanced the all of the tools in the use of tools compare with the EXTERNALITY but some of tools, in particular market-oriented tools, has a very low position. Thirdly,however, "Eco-friendly" tools are listed in some legal documents, but in some documents, the principles of environmental friendliness have been marginalized and as a result, green taxes have not been well-positioned in our legislation.

This paper is organized by using library studies and analytical method, which is explaining the approach that considers economic efficiency as base of law, and has attempted to explain deficiency of this approach. Also, by using pluralistic approach, we can show that bases of responsibility law, cannot be one-dimensional. It is necessary to consider topics such as ethics and justice as well as the base of responsibility in the subject of externalities, in order to reach a more sustainable and efficient social ordering.

This study investigates EXTERNALITY costs of Groundwater overexploitation and its determinants in Mamasani a county of Fars province in Iran. Conditional probability and farmer's marginal willingness to pay on investment for drilling well and/or increasing depth of existence wells as the proxy for negative EXTERNALITY costs were estimated applying Logit and Tobit models to data collected from 135 farmers in the region.The results showed that farmer's willingness to pay for investment of drilling well and/or increasing depth of wells for extraction of water impose relatively high quantity of negative EXTERNALITY costs that farmer's imposes to the society through irregular exploitation of groundwater. Also, the results revealed that credit, size of holding, ratio of irrigated area under vegetables and patch, and ratio of irrigated area under cereals have the highest effects on either farmer's willingness to pay to invest or on negative EXTERNALITY costs. This indicates that despite water scarcity, crop pattern has changed towards high water intensive and profitable crops. Also, the threshold level of holding after which a farmer is willing to invest in drilling well was determined to be 4.76 hectares. Accordingly, it can be concluded that government policy in the field of facilitating water supply has resulted to increasing negative EXTERNALITY cost. In other word, water conservation policies will lead to more destruction of resources if policies are uncoordinated and resource conservation polices are not considered as agricultural supporting polices are performed.

Parmenides and Xenon’s argument for denying motion turned this issue from its obvious form into a theoretical one for the first time. Aristotle showed the possibility of motion with the theory of force and action, but did not offer an argument for the existence of motion. Many philosophers after him, without mentioning the issue of acknowledging the external existence of motion, seem to have taken its EXTERNALITY for granted. Ibn Sina considered the argument for the external objectivity of motion to be metaphysical, yet he made no attempt to prove the external existence of motion. However, we can derive arguments from all of his works and ideas to prove the objectivity of motion. In this article, the theory of grace has been used as an argument for the objectivity of motion. Since grace is the permanence of the divine act, and hindering the series of causes is impossible, the occurrence of time is the same as motion. In other words, the continuity of divine grace is nothing but movement. This movement has manifested itself in material objects. His view of time and its relation to objects is also presented as another argument for proving the EXTERNALITY of motion. Ibn Sina considers the existence of time as a proof of the existence of objects.

Introduction The concept of negative EXTERNALITY is one of interdisciplinary phrases that has been discussed in the field of economic sciences since the last decade of the 19th century. In the following decades, this concept gradually entered the law literature. Although, in nature, it lies within the economic discussions, its main relationship to the field of law is because of the fact that this issue is linked to individuals’ “ownership and responsibility” and negative EXTERNALITY is a clear example of individuals’ responsibility that is necessary to be reflected upon to economize the means of fighting with it.In Iran, one of the few documents that has mentioned the issue of negative EXTERNALITY is the “Wastes Management Act”. In this document and its executive regulations, the legislator has considered the legal arrangements for confrontation with negative EXTERNALITY and has mentioned the tools for this purpose...

Land- phone, like mobile, internet and fax is a communication device and has network EXTERNALITY effect. Thus as the penetration coefficient increases, the network effect improves. The transmission of information via the word of mouth is the main source of enhancing the network externalities coefficient. In this article we have investigated the factors affecting the network EXTERNALITY coefficient.The results show the effects of technical as well as the economical factors on this coefficient. The network EXTERNALITY coefficient is low; but since the shape of S curve diffusion of technology has not yet been completed, the expansion of land- phone network due to demand curve has a main role in the people's willingness to pay for the service of land- phone.

The discussion of externalities occurs when economic action has an impact on people who had no role in making the decision to do so (outside of the exchange or outside the price mechanism). The optimal solution to the problem of externalities created by the ownership of individuals is one of the topics of economics and law, so that externalities can be considered as a bridge between ownership and the economy. There are two categories of theories in solving the externalities problem. The first group of Pigo supporters believes in the use of public mechanisms and government intervention to control externalities. The main tool used by this group is the tax, which causes problems such as the cost of implementation. But the second group of Coase proponents, who believe in resolving externalities with the help of property rights and the use of bargaining tools, believe that by providing a clear and simple definition of property rights, the cost of externalities can be reduced and thus appealing to the courts. Which of these two theories is optimal in terms of law and economics? In this article, these two categories of theories are examined and the external effect is seen as a problem in the world of law and economics. Finally, the position of the proposed solutions has been studied by analyzing the materials related to ownership and liability in Iranian law.

Based on the literature on pollution tax on capital and labor, we have analyzed the impact of an optimal fiscal policy (tax) on the Iran economy based on the Ramsey solution. To achieve this, we created a dynamic economic-climatic model for the Iranian economy by adding externalities to a simple general equilibrium model without a foreign sector. Thus first we developed a dynamic model in two cases with and without side effects. Findings indicate that in the conditions of no pollution of the production sector, the model reaches equilibrium with zero capital tax. When we take into account the pollution in the model, in order to have a unique optimal point and keep the economy on the saddle path and it converged towards an optimal point, so capital-based  pollution tax became essential. In our model, endogenous labor plays an important role as it indicates an increase in household environmental awareness, the supply of working hours, consumption, production, and environmental quality. In the models with exogenous labor, low household awareness of environmental quality leads to more severe degradation of environmental quality. According to our results considering the Ramsey solution on the economy, in a situation where: labor is endogenous, capital-based pollution tax is implemented, with a dynamic general economic-climatic equilibrium model, two environmental parameters are vital to be taken care of, “the weight of environmental quality” and “the polluting technology”. In an environment where we use increasingly polluting technology, in the absence of an increasing pollution tax regime, the quality of the environment and society's welfare will diminish subsequently.